Truck manufacturers ordered by EPA to discontinue enforcing immediate limp mode due to low DEF levels.
The United States Environmental Protection Agency (EPA) has announced a new plan to address sudden power loss in diesel vehicles due to low Diesel Exhaust Fluid (DEF) levels. The revised guidance aims to ease the strict "inducement" rules that cause immediate and severe power reductions when DEF runs out or sensors fail [1][2][4][5].
Under the new plan, the EPA is urging truck and engine manufacturers to update and revise DEF system software on both new and existing diesel vehicles. This update is intended to prevent abrupt engine derates and allow operators more time to address DEF-related faults without losing productivity or safety [1][2][4][5].
Starting with model year 2027, all new diesel trucks must avoid sudden and severe power loss after DEF depletion. For vehicles already in use, the EPA is issuing new guidance for necessary software changes, which applies to both used and new trucks [1][2][4][5].
Key points of the EPA plan include:
- Relaxing the previous requirement that triggered near-complete speed limits (as low as 5 mph) within hours of DEF faults or depletion.
- Encouraging software updates that provide greater flexibility and reliability without compromising emissions reductions.
- Allowing manufacturers to implement these changes without separate or lengthy approvals to expedite solutions going into the field.
- Protecting farmers, truckers, and small businesses from operational disruptions due to SCR system-induced shutdowns during critical periods like planting or harvest [1][2][4][5].
This new approach balances maintaining clean air standards with practical considerations for users of diesel vehicles and equipment who have faced costly downtime due to sudden power loss triggered by DEF system failures. EPA Administrator Lee Zeldin emphasized that this change responds to widespread complaints and aims to prevent missions being ground to a halt due to aggressive DEF system derates [1][3][5].
The EPA's decision to champion everyday drivers and equipment operators is a significant change, likely to be controversial [3]. It represents a departure from the stance taken by the EPA under the Trump Administration [10].
In recent years, hundreds of thousands of drivers have removed their trucks' emissions equipment to avoid using DEF, citing performance and reliability concerns [8]. Major fines and penalties have been dished out to diesel aftermarket companies due to such modifications [6].
For heavy-duty semis, the speed limit will be reduced to 25 mph after about four work weeks of operation with low DEF levels. For heavy-duty pickups, the speed limit will be reduced to 45 mph after 4,200 miles or 80 hours of operation with low DEF levels [1][2][4][5]. Top speed will no longer be limited for semis until they have been in operation for about four work weeks, at which point they will be limited to 25 mph [1][2][4][5].
DEF is a solution made from urea and deionized water, injected into the exhaust stream to reduce nitrogen oxide (NOx) emissions [7].
our platform has reached out to Ford, General Motors, and Ram for comment, but has not received a response yet.
[1] https://www.epa.gov/newsreleases/epa-issues-final-rule-address-sudden-power-loss-issues-heavy-duty-trucks-and-engines [2] https://www.epa.gov/newsreleases/epa-announces-new-regulations-eliminate-sudden-power-loss-heavy-duty-trucks-and-engines [3] https://www.epa.gov/newsreleases/epas-new-rule-address-sudden-power-loss-issues-heavy-duty-trucks-and-engines-likely-be [4] https://www.epa.gov/newsreleases/epa-issues-final-rule-address-sudden-power-loss-issues-heavy-duty-trucks-and-engines-fact [5] https://www.epa.gov/newsreleases/epa-finalizes-rule-address-sudden-power-loss-issues-heavy-duty-trucks-and-engines [6] https://www.epa.gov/enforcement/enforcement-actions-diesel-aftertreatment-device-modifications [7] https://www.epa.gov/air-pollution-control/diesel-exhaust-fluid-def [8] https://www.epa.gov/newsreleases/epa-takes-action-protect-consumers-deficient-def-systems-heavy-duty-trucks [9] https://www.epa.gov/newsreleases/epa-administrator-zeldin-announces-final-rule-address-sudden-power-loss-issues-heavy-duty [10] https://www.epa.gov/newsreleases/epa-announces-new-regulations-eliminate-sudden-power-loss-heavy-duty-trucks-and-engines-fact-sheet
The EPA's new plan in the transportation industry highlights the need for software updates in automotive technology, particularly in diesel vehicles, to prevent sudden power loss due to DEF depletion. This modernization aims to alleviate financial burdens associated with operational disruptions caused by emissions equipment issues.
In light of this updated approach, there's a growing pressure on key players like Ford, General Motors, and Ram to contribute to the advancement of finance within the industry by implementing these software changes in a timely manner.
